PURPOSE: To easily convert a performance substrate by pressing the performance substrate against spring contact pins connected to a pin electronic substrate by using an operation lever and a link mechanism and connecting them.

CONSTITUTION: Lower end parts of the respective spring contact pins implanted in a pin-implanted ring 22 are connected to the wiring pattern (not shown in figure) of a guard board 18 and connected electrically to the pin electronic substrate 12 through connectors 20 and 14. The performance substrate 26 is pressed against the top surface side of the pin-implanted ring 22 by the operation lever and the link mechanism consisting of members 64 and 66, shafts 68 and 70, etc., to connect a contact and (not shown in figure) on the reverse surface of the substrate 26 to the upper end parts of the pins 24. Consequently, no large force is required to attach or detach the performance substrate 26.